Flotation concentration of metalliferous minerals



Patented Nov. 24;, rear umrae srares a OFFICE} HENRY LAYERS AND ARTHUR HOWARD meams, OF LONDON, ENG-14AM, ASSIGNOKS TO MINERALS SEPARATION NORTH AMERIQAN CORPORATION, OF NTE'W.YORK, N. Y.,

A. CORPORATION OF MARYLAND FLOTATION OONOENTRATION OF METALIJFERO'US MINERALS No Drawing. Application filed March 19, 1931, Serial No. 528,928, and in Great Britain January 81,1980. I

. This invention relates to flotation concentration of metalliferous minerals in ores.

In the form of the invention herein illustrated certain flotation agents are added to the ore pulp, in addition to,the usual froth ing agents, so that certain desired constituents of the ore are more effectively selected and floated by amineral-bearing froth, while undesired constituents are more efiectively rejected.

Wehave found thata number of compounds of arsenic are particularly useful for this purpose and may be used with advantage in the differential flotation, of manycomplex ores either alone or in conjunction with flotation agents already known for the purpose of obtaining relatively rich separate con- I centrates of the different economically valuable metals contained in the ores.

The compound of arsenic employed may be a compound of arsenic with an alkali metal, for example sodium. Preferably thearsenic compound also contains sulphur, for exam pleas an alkali thio-arsenate. Alternatively,

:25. arsenious oxide or arsenious sulphide may be added, together with an alkali or an' alkaline sulphide, to the ore pulp. Thus, for example, separation of a lead froth-concentrate cm a mixed lead-zinc ore was obtained by F the use of arsenious sulphide as the flotation agent in conjunction with sodium polysulphide, the zinc being thereafter separated as a zinc froth-concentrate on the-additionof copper sulphate in the known manner. The flotation agent may be added to the ore pulp in a conditioning tank or the like, i but generally it is preferably added in the grinding mill. I

The following examples set forthspecific applications of the invention in practice Example I 4.00 grammes of lead-zinc sulphide ore from the mines of Broken Hill, Australia, were crushed to 100 mesh in a pebble mill in 200 c. c. of water to which were added the following reagents Lbs. er ton 0 ore Sodium thio-arsenate 1. Sodium carbonate 2 Uresylic acid 0.3

The freshly ground ore was then diluted with-Water to form a 4 to 1 pulp and was submitted to agitation and aeration in a mineralsseparation subaeration flotation machine and the froth which formed was taken off-as a lead concentrate. The original ore contained :-Pb=13.-%, Zn=15.1%. The concentrate contained :-Pb=72.3%, Zn= w 6.6%, showing a recovery of 82.5% of the lead, and leaving. 93.2% of the blende unfloated. It will be noted that not only was I the galena effectively separated from the blende during flotation, but that the lead con centrate was of excellent grade showing substantial absence of the other .constituents of the ore.

Thereafter the zinc blende was floated as a separate concentrate in a subsequent operation after the addition of copper sulphate to the pulp at the rate of 1 lb. per ton of ore and of a small amount of frothing agent in the customary manner.

Ewample II- Sulphide ore from Broken Hill was crushed and treated in 'a similar manner to that described in Example 1,-excepting that, in place of sodium thio-arsenate, sodium polysulphide and arsenious sulphide were added to the pebble mill in quantities calculated to theoreticall produce by'reaction an amount. of the sa t sodium thio-arsenate equal to 1 lb. of the salt per ton of ore. The results were as follows :The original ore assayed:-Pb=14.4%, Zn=15.3%. The lead concentrate contained :--Pb=7 3.0%, Zn= 5.3% showing a recovery of 92.0% of the 'total lead and leaving 93.8% of the blende was added equal to 0.5 lb., and Xanthate equal unfloated. In the subsequent flotation -0psists in a itating a pulp of the ore under eration this blende was substantially recovsuch conditions that a float is formed in the ered as a high grade zinc concentrate. presence of a salt of thio-arsenious acid.

Ewam Z6 Ill 4.-. The process of concentrating an ore contaimng two floatable minerals WhlCh con- 400 grammes of lead-zinc tailings, assaysists in agitating a pulp of the ore under such ing Pb=10.7%, Zn=10.3%, from a Durham conditions that a float is formed in the presmine, were recrushed to pass 80 mesh I. M. M. ence of a salt of thio-arsenic acid. in the pebble mill to which were added lime 5. The process of concentrating an ore equal to 2 lbs. per ton of ore, and arsenic containing two floatable minerals which consulphide equal to 0.75 lbs. per ton of ore. sists in a itating a pulp of the ore under The freshly ground ore was then transferred, such conditions that a float is formed by the to a testing flotation machine and diluted use of substances which normallyunite to with water to form a 4 to 1 pulp. Creso1 form a salt of a thio-acid of arsenic.

6. The process of concentrating an ore to 0.05 lb. per ton of ore, and the mixture containing two floatable minerals which conagitated and aerated. A lead concentrate sists in agitating a pulp of the ore under was separated which weighed 50 grammes such conditions that a float is formed in the and assayed Pb=77.0%, zn=2.5% and conpresence of an alkaline. substance and a sultained 90.0% of the total lead. The remainfide of arsenic. ing pulp was further treated with the addi- 7. The process of concentrating an ore contion of copper sulphate equal to 1 1b., creotaining two floatable minerals which consists sote equal to 0.2 lb., and xanthate equal to in agitating a pulp of the ore under such con- 0.1 lb. per ton of originalore, and a zinc conditions that a float is formed in the presence centrate was separated weighing 68 grammes of lime and arsenic sulfide.

and assaying Pb=3.4%, Zn=55.5%, ac- In testimony whereof, we have signed this counting for 91.5% of the total zinc in the specification. ore. The flotation residues assayed Pb= HENRY LAVERS.

0.8% Zn=0.8%,-the Pb being largely in an ARTHUR HOWARD HIGGINS. oxidized condition.

In a similar test on the above tailings the pulp was treated with reagents as in. the above test for 15 minutes in an agitating tank, without any regrinding, and the results obtained were practically identical with the above.

While the invention has been described hereinabove in connection with the separation of lead from zinc, it is also applicable to the separation of copper or other sulphides from associated minerals,.particularly from zinc.

Copper sulphate, as above described, is found to be effective when added to a pulp as a reagent to assist the flotation of a zinc concentrate after the removal of lead.

Thio-arsenites have been found to be effective in producing results like those obtained with thio-arsenates.

Having thus described certain embodiments of our said invention, what we claim 1s:

1. The process of concentrating an ore containing two floatable minerals which consists in agitating a pulp of the ore under such conditions that a float is formed in the presence of an arsenic compound containing suphur.

2. The process of concentrating an ore containing two floatable minerals which consists in agitating a pulp of the ore under such conditions that a float is formed in the presence of a salt of a thio-acid of arsenic.

The process of concentrating an ore containing two floatable minerals which con 

